Context.— The rapid growth of the Internet has triggered an information revolution
of unprecedented magnitude. Despite its obvious benefits, the increase in
the availability of information could also result in many potentially harmful
effects on both consumers and health professionals who do not use it appropriately.

Objectives.— To identify instruments used to rate Web sites providing health information
on the Internet, rate criteria used by them, establish the degree of validation
of the instruments, and provide future directions for research in this area.

Instrument Selection.— Instruments used at least once to rate the quality of Web sites providing
health information with their rating criteria available on the Internet.

Data Extraction.— The name of the developing organization, Internet address, rating criteria,
information on the development of the instrument, number and background of
people generating the assessments, and data on the validity and reliability
of the measurements.

Data Synthesis.— A total of 47 rating instruments were identified. Fourteen provided
a description of the criteria used to produce the ratings, and 5 of these
provided instructions for their use. None of the instruments identified provided
information on the interobserver reliability and construct validity of the
measurements.

Conclusions.— Many incompletely developed instruments to evaluate health information
exist on the Internet. It is unclear, however, whether they should exist in
the first place, whether they measure what they claim to measure, or whether
they lead to more good than harm.